Mutate a data frame by adding new or replacing existing columns.
This function is very similar to
transform but it executes
the transformations iteratively so that later transformations can use the
columns created by earlier transformations. Like transform, unnamed
components are silently dropped.
- the data frame to transform
- named parameters giving definitions of new columns.
Mutate seems to be considerably faster than transform for large data frames.
# Examples from transform mutate(airquality, Ozone = -Ozone) mutate(airquality, new = -Ozone, Temp = (Temp - 32) / 1.8) # Things transform can't do mutate(airquality, Temp = (Temp - 32) / 1.8, OzT = Ozone / Temp) # mutate is rather faster than transform system.time(transform(baseball, avg_ab = ab / g)) system.time(mutate(baseball, avg_ab = ab / g))